First, congrats on your girls! As someone who is in a trio of sisters herself, it's pretty great <3
My favorites from your list:
Olive - This is one of those names where I love the whole and all the nicknames with equal measure. I think it's beautiful and I adore Liv, Olly and "O"
Cleo - short, so cool and spelling intuitive, a name I'd love to have
Cosette - always had a special place in my heart for this one, I just think it's gorgeous
Juniper - I love this name, I think it's fun and pretty.
Maeve - Really like this name! I always immediately think, Maeve Josette with the nn MJ<3
Esme, Aubrey, Margot, Delilah, Ottilie - all of these give me the same 'meh'. Absolutely nothing wrong with them, just popular and don't spark joy lol
Edith, Flora, Iris - Objectively I know they are classics, but to me they just sound dated.
Other ideas you may like:
you didn't ask for combos, but since you mentioned the big sisters had two middle names, I thought it would be fun lol
Eden Aubrey Maeve
Shay Florence Cassidy
Jennifer Lara Carys
Blaire Ivy Madeleine
Tess Margot Emma
Isobel Maeve Cosette
Piper Lily Esme
Eve Adrienne Violet
Celeste Taylor Whitney
Brooke Adrienne Violet
Odette Iris Maisie
(Gigi) Gemma Grace Caroline
Raven Thea Quinn
Hazel Alix Aria
Renee Flora Belle
Daisy Jane Matilda
Natalie Noa Claire